Obtained by alkaline hydrolysis of protoveratrine A: Poethke, Arch. Pharm. 275, 571 (1937); Stoll, Seebeck, Helv. Chim. Acta 36, 718 (1953). Structure: Kupchan et al., Chem. Ind. (London) 1958, 1626; J. Am. Chem. Soc. 81, 1009 (1959); 82, 2242 (1960). Comparative toxicity: O. Krayer et al., J. Pharmacol. Exp. Ther. 82, 167 (1944); K. Tanaka, ibid. 113, 89 (1955).